I m using RB750 and using static ip for my clients. now i want to setup hotspot in the same interface. but when it is done ping to static ip says "Destination host is unreachable". Please help me that what is the problem and how can i use both static ip client and hotspot client?

There is no issues with static IPs and hotspots. Is the host you're trying to ping logged in, or at least bypassed? If it isn't of course traffic to/from it would be dropped, after all that is what a Hotspot does.

If you need to ping even unauthenticated hosts you can allow ICMP in the walled garden IP level.

I have used 192.168.0.1 for static ip in router LAN interface and run hotspot in that interface with that ip. If i want to ping to router when hotspot is running it says Destination host is unreachable. But when i disable the hotspot it works fine. what's the sollution?

Did you read my post?

Either log the device in, or bypass it in "IP hotspot ip-binding".

you should be able to ping the Gateway ip ( hotspot ip ) if not you should check the ARP config on that interface, should be "enable" if you want to get ping replay,

To ping GW with is HotSpot you furst need to login
this is normal coz hotspot try to redirect to login page
caprive portal basic's

If you want users to be able to ping without logging in you could whitelist ICMP in the walled garden.